Electrode for arc lamps



(No Model.)

I. L. ROBERTS. ELECTRODE FOR ARC LAMPS.

No. 460,596. Patented Oct. 6, 1891.

Carbon and C/Pramiz/m WITNESSES INVENTOR W M$W mama, BY

IOZLLLLM yS AT T ORNE Y9 UNITED STATES PATENT OFFICE.

ISAIAH L. ROBERTS, OF BROOKLYN, NEIV YORK.

ELECTRODE FOR ARC LAMPS.

SPECIFICATION forming part of Letters Patent No. 460,596, dated October 6, 1891.

Application filed March 6, 1891.

To all whom it may concern:

Be it known that I, ISAIAH L. ROBERTS, a citizen of the United States, and a resident of Brooklyn, in the county of Kings and State of New York, have invented certain new and useful Improvements in Arc-Lam p Pencils, of which the following is a specification, reference being had to the drawing accompanying and forming part of the same.

The subject of my present lnvention is a pencil or electrode for are lamps which is an improvement on the carbon and other pencils in general use in the particulars hereinafter pointed out.

This invention is an improvement on the form of arc-light pencil shown and described in my application filed March 10, 1890, Serial No. 343,315, and which consists, broadly, of a pencil composed of a metallic holder, with which is associated a refractory substance containing chromium or some of its compounds.

According to my presentinvention I employ as the refractory substance a compound of conducting-carbon and a substance containing chromium, finding that by so doing lobtain a superior light and a more durable carbon, which, particularly after the extinguishment of the arc, offers a lower resistance and relights more readily. I also employ as the metallic holder a cylinder rod ortube of wiregauze, the use of which contributes very greatly to reducing the cost of manufacture.

In carrying out my invention I use, generally, a wire net or gauze of about twelve meshes to the inch. Strips of this are rolled up into rods or tubes of the desired diameter, which are pressed down into a mixture of about ten per cent. of plumbago or some conducting Serial No. 383,941. (No model.)

carbon, gasretort carbon, and ninety per cent. of pulverized chrome iron ore or other compound of or containing chromium. The chrome-iron ore should beas free from earthy matters as possible, and it is made into a mud by a solution of caustic soda of about 10 Baum. If a perforated tube or cylinder, such as is made of wire-gauze, be forced down into such a mixture and rapped repeatedly, the mud rapidly works in through the perforations or meshes and completely fills it. This material dries rapidly and becomes hard and solid, and when so dried a coating of the same compound is applied over the tube.

In theaccompanying drawing a pencil constructed in the manner above described is shown partly in section.

B is the Wire-gauze, and O the chromium compound and carbon.

Having now described my invention, what I claim is 1. A pencil for are lamps, composed, essentially, of carbon and a substance containing chromium, in combination with a metallic conductor or holder with which it is associated, as set forth.

2. A pencil forarc lamps, composed of a re fractory compound containing chromium, in combination with a tube or cylinder of perforated metal, such as wire-gauze.

3. Apencil forarclamps, composed ofa mixture of carbon, a substance containing chromium, and causticpotash, in combination with a holder of wire-gauze.

ISAIAH L. ROBERTS. Witnesses.

RoBT. F. GAYLORD, PARKER W. PAGE. 

